An inkjet image forming device forms images in predetermined colors by ejecting fine ink droplets from an inkjet head to a desired location on a printing medium. Generally speaking, inkjet heads may be classified in one of two types according to the mechanism being employed for ejecting ink droplets; a thermal type and a piezoelectric type. A thermal type inkjet head inkjet head produces ink bubbles using a thermal source, and ejects ink droplets as the bubbles expand. A piezoelectric type inkjet head, on the other hand, ejects ink droplets by applying pressure to the ink using deformation of a piezoelectric element.
In a thermal inkjet head inkjet head, when a pulse of electric current flows in a heater, e.g., formed of a resistive heating material, ink adjacent to the heater becomes instantaneously heated to a high temperature, which could be, e.g., approximately 300° C. by the heat produced by the heater, causing the ink to boil, and to produce ink bubbles. As the generated bubble(s) continue to expand and to thereby exert pressure to surrounding ink filled in an ink chamber, the ink close to a nozzle is ejected to the outside of the ink chamber as ink droplets.
The inkjet head may manufactured as a chip, and may have a structure in which a chamber layer and a nozzle layer are sequentially stacked on a substrate. The chamber layer includes a plurality of ink chambers that are to be filled with ink, whereas the nozzle layer includes a plurality of nozzles through which the ink is ejected from the ink chambers. Additionally, an ink feed hole for supplying ink to the ink chambers may be formed through the substrate. In an inkjet head having the above described structure, the ink feed hole formed through the substrate may present a structural weakness in, or, in some instances, deformation of the substrate. In practice, the inkjet head described above may be mounted on a base header, which may also include formed therein ink supply paths corresponding to the ink feed holes. The ink feed holes in the inkjet head substrate and/or the ink supply paths in the base header tend to reduce the mounting or adhesive surface area of the inkjet head and the base header. Misalignments of the ink feed holes and the corresponding ink supply paths may also occur.